It has long been known that in the making of ice-cream it is necessary to stir the ice-cream mix while freezing it. If this is not done large ice crystals form making the product unpalatable. In the earlier forms of domestic ice-cream makers this was achieved by the use of an outer container having within it a rotatable inner container. The space between the two containers was filled with a mixture of ice and salt and the ice-cream mix was placed in the inner container and the inner container rotated, the ice-cream mix being stirred by means of a fixed mixing blade. Alternatively, the mixing blade was rotated. Ice-cream makers of this kind are at present in use and, whereas in the earliest forms, the rotation was carried out by hand it is now usually carried out by means of an electric motor. Such ice-cream makers are effective but they are relatively cumbersome and inconvenient to use by reason of the necessity of preparing a mixture of crushed ice and salt.
Another form of domestic ice-cream makers consists in what is in effect, a miniature freezer, the apparatus incorporating a refrigerating unit and a means for stirring a ice-cream mix in a container. Such ice-cream makers are extremely effective but, by reason of the necessity of providing a refrigerating apparatus, they are expensive.
A third form of apparatus has been marketed consisting simply of a container having within it a rotatable mixing blade driven by a small electric motor which is powered through a connecting cord by means of which the motor is connected to the electric mains. Such ice-cream makers are simply placed in the freezing compartment of a conventional refrigerator, the connecting cord is led out of the refrigerator through the door seal and connected to the electric mains. Stirring is carried on until the ice-cream mix has reached the desired consistency. In some ice-cream makers of this sort a thermostatic control is provided so that when the consistency of the ice-cream mix is such as to cause the motor to overheat a thermostat switch switches the motor off. In some ice-cream makers of this sort the ice-cream mix is contained in a simple metal container and the ice-cream mix is chilled simply by its presence in the freezer compartment. In one form of apparatus, however, an electric motor is not only used to rotate a mixing blade in the ice-cream mix container but also to drive a small fan which acts to draw in air around the bottom of the container and up its sides. This does, to some extent, speed up the freezing of the ice-cream mix.
Domestic ice-cream makers of the last described category, despite being quite effective and inexpensive, have not achieved a high degree of popularity. This is believed to be due to an irrational fear on the part of users of introducing into a refrigerator a mains powered electrical device. This is despite the fact that in some cases the voltage applied to the motor is only 24 volts.
One object of the present invention is to provide domestic ice-cream makers of the third category in which the use of a mains connection is dispensed with by providing a battery pack which forms part of the ice-cream maker. While this concept is simple enough it was found in practice extremely difficult to construct an ice-cream maker which would make ice-cream with a battery pack of an acceptable size. After considerable experiment it was found that the solution to the problem lay in the provision of a fan which blew cold air from the freezer compartment directly into the ice-cream mix while it was being stirred. By doing this it was found possible to make ice-cream of an acceptable consistency during the life of a pack of six commercially available rechargeable cells.
A further object of the invention is to provide a domestic ice cream maker of the third category of improved effectiveness insofar as the time required for making the icecream is shortened and in that the quality of the product is somewhat better, whether the apparatus is driven from a battery pack or from mains. These improvements are achieved by the use of a fan or other means to blow cold air from the freezer compartment directly onto the icecream mix. In this connection, it has been found that if instead of using a single fan for this purpose two fans arranged side by side are used still further improvements in the results are obtained.